The present invention relates to a bushing liner for rotatably mounting a pin in a bushing on an endless chain of a textile machine traveling web transport assembly.
It is known in textile machine traveling web transport assemblies to provide a pair of spaced endless chains, each supporting a plurality of web engaging members such as, for example, vertical pins, onto which one edge portion of a textile web is impaled for transport of the textile web through a tenter frame or other textile machine which handles the web. Each endless chain includes a plurality of links, each respective adjacent pair of links being interconnected to one another by a pin. Each pin is rotatably supported by a bushing mounted to one of the pair of links and one known arrangement for rotatably mounting a pin in a bushing includes an annular bushing liner between the pin and the bushing.
In a tentering frame chain disclosed in U.S. Pat. No. 4,926,529, there is disclosed a sliding bushing liner made of synthetic resin, and produced in a way that a plastic part of the material is first pressed into the supporting bushing liner, preferably made of steel, and a bore is then made to finish the sliding bushing liner.
By boring the sliding bushing liner, which is secured against twisting by pressing it into the supporting bush, the wall thickness of the sliding bushing liner can be brought to a minimum dimension necessary for the manufacture of a greaseless bearing so that, when the chain is under tension in operation, the length of the chain will not significantly change due to the fact that the sliding bushing accommodates the tension through corresponding increases and decreases in its thickness and, accordingly, the chain will show no alteration in length. The pressing in and boring of the sliding bushing liner, however, is a work-intensive step of process during the manufacture of the chain.
One suggested approach is to prefabricate the sliding bushing liner of synthetic resin and loosely insert it into the space between supporting bush and joint bolt. Thermal and/or mechanical strains, however, cause breaking of the sliding bushing, which is more intended for minimal friction than for mechanical strength. A sliding bushing made of synthetic resin loosely inserted into the space between supporting bush and the joint bolts is in addition intended to be firmly positioned as specified, which avoids the sliding bushing to partly or wholly slip out of the space between supporting bush and joint bolt and to the bottom, either during assembly or when in operation.
Therefore, the need exists for a bushing liner made of high-temperature resistant synthetic resin, that is loosely to be inserted between supporting bushing and joint bolts of the jointpart of a tentering frame chain, that which remains stable even in spite of strongly varying and extreme mechanical and thermal stresses as typical for stretching machines for web of cloth. Additionally, the need exists for a sliding bushing which can easily be inserted from top or from a side into the supporting bushing during assembly.